Apple CEO Tim Cook says that he remains “bullish,” but the numbers suggest that this is little more than putting a brave face on things.

The problem facing the iPad is that it’s past its peak. In fact, “peak iPad” was three years ago, when in 1Q 14 Apple sold 26 million iPads.

It’s been downhill from there, with little blips of increased interest around the holiday period.

Comparing the last quarter to “peak iPad” three years ago, iPad sales have halved.

Here’s what sales look like:

iPad quarterly sales

Apple should be worried about that. Why? Because the chart should be all too familiar to the company. Here are quarterly sales of another Apple product that once seemed unstoppable but is now pretty much forgotten – the iPod.

iPod quarterly sales

See the similarities? You should. But in fact, the iPad’s trajectory is worse than that of the iPod. While iPod sales never got as high that that of the iPad – it hit a peak of 22.7 million in 1Q 09 – it took the iPod four years (or 16 quarters) before sales halved.